This invention is directed to gelled hydrocarbon compositions which are stabilized to the presence of excess base. More particularly this invention is directed to gelled hydrocarbon compositions comprising liquid hydrocarbons, pseudo double salt gelling agents prepared from partial aluminum salts of alkyl acid orthophosphates by neutralizing with an inorganic base and a stabilizer to prevent breakdown by excess base, said stabilizer being an anhydride of a carboxylic acid, and to a method for stabilizing the hydrocarbon gels.
Partial aluminum salts of certain alkyl acid orthophosphates, when further neutralized with an inorganic base such as sodium hydroxide, ammonium hydroxide or the like, form pseudo double salts which are effective gelling agents for hydrocarbons. Hydrocarbon gels formed with these pseudo double salts are thixotropic, exhibiting high viscosity at rest and under low shear conditions and thus are capable of suspending large quantites of particulates such as sand without settling. These gels, even at very low concentrations, exhibit the ability to reduce fluid friction of hydrocarbons during high speed flow through pipes and orifices, thus decreasing the energy required to maintain fluid flow.
While these pseudo double salts have found a variety of applications where thixotropic gel properties and/or reduction in fluid friction are desired, their utility has been somewhat limited and their handling made more difficult by a high degree of sensitivity to alkalis. The hydrocarbon gels are formed only at or very near neutralization, and the presence of excess base either prevents formation of a gel or quickly destroys the gels once they are formed. For that reason it has not been possible to employ these pseudo double salts to prepare gelled compositions containing as suspended or dissolved components such materials as highly alkaline particulates or epoxy resins together with the commonly employed alkaline curatives. Additionally, formation of the gels requires care and precision in the neutralizing step to ensure that only a neutralizing amount of the base is added, thus making handling under field conditions by unskilled personnel difficult and subject to great risk that improper technique will result in high volumes of ungellable product.